JP2012219161A - Oil-based ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide oil-based ink which can be well fixed even to paper with few voids such as glossy paper.SOLUTION: This oil-based ink includes at least a dye and an organic solvent, wherein the dye is contained in an amount of 0.1-20 mass% relative to the total amount of the ink, and the organic solvent contains 50-99 mass% of a five-membered heterocyclic compound having a C=O bond or a phosphoric acid ester relative to the total amount of the ink.

Description

  The present invention relates to an ink suitable for use in an ink jet recording system, and more particularly to an oil-based ink containing a dye as a coloring material.

 Inkjet recording is a method in which high-fluidity inkjet ink is ejected as ink particles from fine head nozzles, and images are recorded on printing paper placed facing the nozzles, enabling high-speed printing with low noise. In addition, since variable data can be output at low cost, it has been rapidly spreading in recent years. Inks used in the ink jet recording system are roughly classified into aqueous, solvent and oily.

 Oil-based inks are less likely to volatilize than solvent inks, so they are safer and easier to maintain. They do not cause cockling or curling like aqueous inks, making them suitable for inkjet recording systems that perform high-speed printing. The ink is widely used as an ink (for example, Patent Document 1).

 By the way, when printing ink is classified by drying method, it is roughly divided into a penetrating drying method that penetrates and dries printed matter such as paper, a volatile drying method in which the ink volatilizes and dries after printing, and a polymerization drying method in which the ink itself dries and solidifies. It is divided into.

JP 2007-126564 A

Oil-based inks are difficult to volatilize and dry because they use a low volatility solvent, and rely exclusively on osmotic drying. For this reason, when oil-based ink is used for paper having a small gap such as glossy paper, there is a problem that the ink is not fixed because the ink hardly permeates.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an oil-based ink that can be satisfactorily fixed even on paper with few voids such as glossy paper.

The oil-based ink of the present invention is an oil-based ink containing at least a dye and an organic solvent, wherein the dye is 0.1 to 20% by mass relative to the total amount of the ink, and the five-membered member having a C═O bond in the organic solvent. A heterocyclic compound or a phosphate ester is contained in an amount of 50 to 99% by mass based on the total amount of the ink.
The five-membered heterocyclic compound is preferably at least one selected from carbonate compounds, lactone compounds, imidazolidinone compounds, and pyrrolidone compounds.

The carbonate compound is preferably at least one selected from ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, and derivatives thereof.
The lactone compound is preferably at least one selected from γ-butyrolactone, α-acetyl-γ-butyrolactone, pentano-4-lactone, and derivatives thereof.

The imidazolidinone compound includes 2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, 1, It is preferably at least one selected from 3-diisopropyl-2-imidazolidinone, 1,3-dibutyl-2-imidazolidinone, and derivatives thereof.
The pyrrolidone compound is preferably at least one selected from 2-pyrrolidone, N-methyl-pyrrolidone, 1-ethyl-2-pyrrolidone and derivatives thereof.

The content of the polymer component in the ink is preferably 1% by mass or less based on the total amount of the ink.
Here, the polymer component means a polymer having a repeating structure of a monomer (monomer) and having a molecular weight of 500 or more.

  In the oil-based ink of the present invention, the dye is 0.1 to 20% by mass based on the total amount of the ink, and the five-membered heterocyclic compound or phosphate ester having a C═O bond in the organic solvent is 50 to 50% based on the total amount of the ink. Since it contains 99% by mass, it can be satisfactorily fixed even on paper with few voids such as glossy paper. Although the mechanism of this action is not always clear, 5-membered heterocyclic compounds and phosphate esters have the property of dissolving dyes well, and these 5-membered heterocyclic compounds and phosphate esters have low viscosity, and these 50 to 99 mass% of the total amount of the ink is contained, so that even in paper with few voids, the dye can easily penetrate into the inside of the paper by capillary action and promote fixing on coated paper and glossy paper. It is considered possible.

In order to promote fixing on glossy paper, it is effective to reduce the amount of ink transfer. However, in the case of conventional oil-based inks, reducing the amount of ink transfer can lower the image density, which sacrifices image density. Even if the amount of transfer was reduced, fixing to glossy paper was not at a sufficient level. On the other hand, in the case of the oil-based ink of the present invention, the five-membered heterocyclic compound and the phosphate ester dissolve the dye well, and these solvents are contained in an amount of 50 to 99% by mass based on the total amount of the ink. Even under a small condition, it is possible to easily obtain an image density and to form a good image quality.
Therefore, the oil-based ink of the present invention can be suitably used as glossy paper ink.

  The oil-based ink of the present invention (hereinafter also simply referred to as ink) is an ink containing at least a dye and an organic solvent. The dye is 0.1 to 20% by mass with respect to the total amount of the ink, and a C═O bond in the organic solvent. It is characterized by containing 50 to 99% by mass of a five-membered heterocyclic compound or phosphate ester having

  The five-membered heterocyclic compound may be a liquid or a solid, and in the case of a solid, any compound that dissolves in an organic solvent may be used. As the organic solvent to be dissolved, an organic solvent described later can be used. Preferred examples of the 5-membered heterocyclic compound include carbonate compounds, lactone compounds, imidazolidinone compounds, and pyrrolidone compounds.

Preferred examples of the carbonate compound include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, and derivatives thereof.
Preferred examples of the lactone compound include γ-butyrolactone, α-acetyl-γ-butyrolactone, pentano-4-lactone, and derivatives thereof.

Examples of the imidazolidinone compounds include 2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, Preferable examples include 3-diisopropyl-2-imidazolidinone, 1,3-dibutyl-2-imidazolidinone and derivatives thereof.
Preferred examples of the pyrrolidone compound include 2-pyrrolidone, N-methyl-pyrrolidone, 1-ethyl-2-pyrrolidone and derivatives thereof.
Examples of the derivative include compounds in which a hydrogen atom is substituted with a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

  Preferred examples of the phosphoric acid ester include phosphoric acid monoester, phosphoric acid diester, and phosphoric acid triester, and more specifically, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triisopropyl phosphate, phosphorus Preferable examples include tripropyl acid, triamyl phosphate, triphenyl phosphate and derivatives thereof. Examples of the derivative include a compound in which a hydrogen atom is substituted with a fluorine atom or an alkyl group having 1 to 4 carbon atoms.

  The five-membered heterocyclic compound or phosphate ester may be used alone or in combination of two or more. In addition, when using in combination of 2 or more types appropriately, it means that the total content of the 5-membered heterocyclic compound and the phosphate ester used in combination is 50 to 99% by mass with respect to the total amount of the organic solvent. To do. More preferably, the total content of the five-membered heterocyclic compound or phosphoric acid triester is 60 to 97% by mass with respect to the total amount of the ink. Since the 5-membered heterocyclic compound or phosphate ester has a low viscosity, it can be more suitably used as an inkjet ink.

  The content of the polymer component in the ink is 1% by mass or less, preferably 0.5% by mass or less, based on the total amount of the ink. In the case of a polymer having a curing property, if the polymer component exceeds 1% by mass, nozzle clogging occurs, which is not preferable. In the case of a polymer that does not have a curing property, the polymer component is difficult to penetrate into glossy paper and coated paper. Therefore, if the polymer component exceeds 1% by mass, the ink fixability is lowered, which is not preferable.

  As a polymer component in the ink, when a polymer dispersant is included, for example, as a commercial product, Solsperse series (Solsperse 18000, 28000, 11200, 20000, 27000, 41000, 41090, 43000) manufactured by Nippon Lubrizol Corporation. 44000), Jonkrill series (Johnkrill 57, 60, 62, 63, 71, 501) manufactured by BASF Japan, and polyvinylpyrrolidone K-30, K-90 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and the like.

  When resin is included, Marquide NO. 31, NO. 32, NO. 33, Marquide NO. Styrene acrylic resins such as 32-30WS maleic acid resin, Tamano 751 manufactured by Arakawa Chemical Industry Co., Ltd., phenol resin such as Tamanoru PA, Jonkrill 682 (trade name) manufactured by BASF Japan, Tachikasei Kogyo Co., Ltd. High-rack 111, 110H, etc. made of ketone resin, Nippon Steel Chemical Co., Ltd., Escron G90, V120, etc. Coumaron resin, Chisso Co., Ltd., Vinylec E type, K type, etc., Polyvinyl formal resin, Ube Industries, Ltd. Ε-caprolactam copolymer such as nylon 6 manufactured by Sekisui Chemical Co., Ltd., Polysethyl butyral resin such as ESREC BL-1 and BL-2, polystyrene such as Astyka Chemical Co., Ltd. Such as polyacrylic acid ester, polymethyl methacrylate, Polymethacrylates such as propyl methacrylate, addition polymerization resins such as chlorinated polypropylene, polyvinyl acetate, maleic anhydride polymer, acrylonitrile / butadiene / styrene resin, chlorinated polypropylene, DFK resin, polyester, polyurethane, polyamide, etc. Examples include condensation polymerization resins.

The organic solvent contained in the ink of the present invention may be a 5-membered heterocyclic compound or a phosphate ester, but may contain other organic solvents. Examples of organic solvents other than the five-membered heterocyclic compound or phosphate ester include water-soluble organic solvents and petroleum hydrocarbon solvents. Specific examples include ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol. , Pentaethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and other glycols, glycerin, acetins, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, tetra Glycol derivatives such as ethylene glycol diethyl ether, triethanolamine, β-thioglycol, sulfolane, AF-7, AF- Or the like can be used a hydrocarbon solvent such as. These water-soluble organic solvents can be used alone or in combination of two or more.
The content of the organic solvent is preferably 40% by mass or less in the total amount of ink from the viewpoint of ink viscosity.

  As the dye used in the ink of the present invention, conventionally known dyes can be used. Azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, cyanine dyes, quinoline dyes More preferred are oil-soluble dyes such as nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes and metal phthalocyanine dyes. These dyes may be used alone or in combination as appropriate, but in the range of 0.1 to 20% by mass, more preferably 1 to 10% by mass with respect to the total amount of the ink. It is desirable to contain in a range. If it is less than 0.1% by mass, the printing density is remarkably lowered, and if it exceeds 20% by mass, the scratch resistance is lowered.

  In addition to the above components, the ink of the present invention may contain conventional additives. Additives include surfactants such as anionic, cationic, amphoteric or nonionic surfactants, antioxidants such as dibutylhydroxytoluene, propyl gallate, tocopherol, butylhydroxyanisole, and nordihydroguaiare. And tic acid.

The ink of the present invention can be prepared by, for example, supplying all components in a known disperser such as a bead mill in a batch or divided and dispersing them, and if desired, passing them through a known filter such as a membrane filter.
Examples of the ink of the present invention are shown below.

(Preparation of ink)
The raw materials were mixed with the composition shown in Table 1 below (the values shown in Table 1 are parts by mass), stirred with a stirrer for 1 hour, and filtered with a membrane filter having a pore size of 3 μm to obtain inks of Examples and Comparative Examples. .

(Image collection)
Images were collected under the following conditions.
Head: CB2 head (manufactured by Toshiba Tec Corporation)
Resolution: 300 dpi x 300 dpi
Image: Monochromatic solid 1-dot droplet volume: 42pL
Paper: Glossy paper (Mitsubishi Chemical Media, Seiko Epson, DNP Photo Marketing)

(Fixability evaluation)
30 seconds after the image was printed, the ideal paper IJ mat (W) was placed on the printing surface, and the paper was reciprocated five times with a plastic roller. The degree of stain transferred to the IJ mat (W) was visually evaluated according to the following criteria.
：: No stains are confirmed. ○: The stains are negligible and not noticeable. Δ: Slightly noticeable stains. X: The stains are conspicuous. Table 1 shows the formulation and evaluation results of each ink.

  As shown in Table 1, the inks of the present invention shown in Examples 1 to 12 had good fixability in any of the three types of glossy paper. Example 10 is an ink containing 1% by mass of a polymer component with respect to the total amount of the ink, but it is considered that the fixability was worse than in other examples because the polymer component hardly penetrates into glossy paper. In Example 12, the content of the dye was very high at 20% by mass, and a large amount of coloring material was likely to remain on the paper surface. Therefore, although the difference was slightly different from the other examples, the fixability was lowered.

  Comparative Example 1 is a pigment ink, and Comparative Example 2 is a dye ink. In this case, the pigment or dye is only dispersed in an organic solvent such as a higher alcohol solvent, an ester solvent, or a petroleum solvent by a dispersant. On the other hand, since these organic solvents do not penetrate into glossy paper with few voids, the fixability is remarkably poor. In Comparative Example 3, the content of the dye is as large as 25% by mass, so that the limit of the amount penetrating into the paper due to the capillary phenomenon was exceeded, so that the fixing property was deteriorated.

  As described above, the oil-based ink of the present invention has the property that the five-membered heterocyclic compound or phosphate ester having a C═O bond in an organic solvent dissolves the dye well, and these solvents are used in the total amount of the ink. 50% to 99% by mass with respect to the amount of ink transferred, it is possible to form a good color on glossy paper even under conditions where the amount of ink transfer is small, to obtain an image density, and to form a good image quality. Even under many conditions, the dye easily penetrates into the paper due to the capillary phenomenon, and the fixing can be promoted.

Claims (8)

  An oil-based ink containing at least a dye and an organic solvent, wherein the dye is 0.1 to 20% by mass relative to the total amount of the ink, and a five-membered heterocyclic compound or phosphoric acid having a C═O bond in the organic solvent An oil-based ink comprising 50 to 99% by mass of an ester based on the total amount of the ink.   2. The oil-based ink according to claim 1, wherein the five-membered heterocyclic compound is at least one selected from a carbonate compound, a lactone compound, an imidazolidinone compound, and a pyrrolidone compound.   The oil-based ink according to claim 2, wherein the carbonate compound is at least one selected from ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, and derivatives thereof.   The oil-based ink according to claim 2, wherein the lactone compound is at least one selected from γ-butyrolactone, α-acetyl-γ-butyrolactone, pentano-4-lactone, and derivatives thereof.   The imidazolidinone compound is 2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, 1, The oil-based ink according to claim 2, wherein the ink is at least one selected from 3-diisopropyl-2-imidazolidinone, 1,3-dibutyl-2-imidazolidinone, and derivatives thereof.   3. The oil-based ink according to claim 2, wherein the pyrrolidone compound is at least one selected from 2-pyrrolidone, N-methyl-pyrrolidone, 1-ethyl-2-pyrrolidone and derivatives thereof.   7. The oil-based ink according to claim 1, wherein the content of the polymer component in the ink is 1% by mass or less based on the total amount of the ink.   The oil-based ink according to any one of claims 1 to 7, which is an ink for glossy paper.